The Girl Who Thawed
by TheLaurax
Summary: Anna is famous among the wizarding world because of surviving being struck by ice. Her sister Elsa, with abnormal ice magic, has run away and is a potential threat to society. What will happen when Anna goes to Hogwarts and tries to stop her sister from freezing everything? Not exactly a cross-over, just a mix up of the stories of Frozen and Harry Potter. Frozen characters. AU
1. Prologue

**A/N: Hey everyone, here I am again with another fic. This technically isn't a crossover, I just put the characters of Frozen in another story (Harry Potter!). Not everything is the same as the real Harry Potter story, I purposely changed a few things. I will try to update as often as possible, which still will probably not be too often, as I have another ongoing fic and I'm busy with school and things as well. Remember, I don't own anything.**

_Anna POV_

"Psst! Elsa!" I climb up onto my sister's bed. "Wake up, wake up, wake up!"  
She groans. "Go back to sleep, Anna."  
"I can't! It's a full moon. We have to play!"  
"Go play by yourself." She gives me a nudge and I fall off the bed.  
Jumping back on, I hold back a smile and open one of her eyes. "Do you wanna build a snowman?"  
She opens both and sits up. I grin. "Let's go!"  
We quietly open our bedroom door and tiptoe past our parents' room. I grab her hand and pull her down the stairs. "Come on, come on, come on!"  
"Shh!" She silences me, but even so she's laughing herself.  
Finally, we reach the basement.  
"Do the magic, do the magic!"  
She holds out her hands and forms a snowball. "Are you ready?"  
I nod excitedly. She lets go of the snowball and it launches into the air, bursting into millions of tiny snowflakes.  
I giggle. "This is amazing!"  
Soon, snow blankets the whole floor. We set to work building a snowman.  
Elsa stands behind it. "Hi, I'm Olaf and I like warm hugs!" she says in a silly voice.  
"Wait a second," I say, holding my own hands out. I close my eyes and concentrate really hard.  
Elsa gasps and claps. "Yay, Anna, you did it!"  
I open my eyes and see the snowman's arms moving up and down.  
"It looks like it's waving!" Elsa says, smiling.  
"I actually did it tonight!" I say, but my grin fades. Elsa notices.  
"Anna, what's wrong?"  
"I just-" I sniffle. "I wish I was like you. You can control snow and ice! Your magic is different. I'm just the same as any other witch. All I can do is make a snowman's arms move," I pout.  
Elsa takes my hand. "Anna, someday you'll become the greatest witch they'll ever be. Trust me."  
I look up at her. "Really?"  
She smiles at me. "Really." She then gestures to all the snow once more. "Sooo... Do you wanna go sledding?"  
I grin.

* * *

We've wasted the time away, Elsa and I, just playing in the basement. Her powers can make anything with ice and snow, and I love it.

"Catch me!" I scream in delight, jumping off a snow mound. Elsa smiles and creates another snow pile. "Catch me!" I say again, leaping into the air. Another mound appears.  
"Catch me! Catch me! Catch me!"  
"Slow down!" Elsa says, barely keeping up. And then I jump. "Catch me!"  
Elsa slips. Ice shoots in all directions. And hits me.

_Elsa POV_

"Slow down!" I say, barely keeping up with Anna's jumps.  
She leaps into the air again. "Catch me!" she screams happily. I know I won't catch her in time.  
My foot slips. Ice shoots everywhere.  
I hurriedly get to my feet. "Anna!"  
She's lying in the snow, unconscious. I run over to her. "No!"  
Her hair is turning white, her lips blue. Her skin is ice cold.  
"Mummy! Daddy!" I call them in despair.  
I hold Anna's head in my lap. "You'll be okay, Anna. I've got you."  
Mum and Dad burst into the basement. "Oh Elsa, what have you done?" Dad sees Anna, and his face is overcome with worry. I hear him take a deep breath. "I know where we have to go."  
Mum takes my hand and Dad picks up Anna. He looks at Mum for a brief moment, and a silent understanding passes between them.  
"We're going to do side along apparation, alright?" Mum says. "Just hold tight to my hand."  
There's a loud crack, and suddenly I'm not at home anymore, but in front of a large castle. I grip Mum's hand tighter.  
Dad and Anna appear right next to me. "Come on," he says. "This way." He and Mum start walking in the direction of the big metal gates.  
Immediately a ratty looking man and a cat walk around the gate. "Who are you?" the man asks gruffly, eyeing us suspiciously.  
"Georg and Emmeline Arendelle. We are good friends with the headmaster. We need to speak with him right away. It's urgent." Dad gives the man a pleading look.  
"Fine," the man grumbles. "I take it you know where the headmaster's office is?"  
"Yes, of course. Thank you."  
The man walks back around the gates and disappears. Slowly they creak open.  
Dad takes my hand as well. I hold both his and Mum's tighter. He adjusts his grip on Anna. We all walk forward into the castle.

* * *

Dad knocks on the big wooden door. "Kai? Mr. Borgen? It's me, Georg Arendelle. I need your help. It's an urgent matter."

We wait for a little bit. The door slowly swings open. "Georg?" A tall man in long, dark blue robes stands in the doorway. "What is it you need my assistance of?" Then he catches sight of Anna. "Oh dear."  
We all walk in. Dad carefully places Anna down on the table. She looks a lot worse: white hair, blue lips, pale skin. I grimace.  
"Well, well, well. What do we have here?" the headmaster (Mr. Borgen?) asks, examining Anna. I try to hide behind the folds of my mother's robes. It's too hard to look at.  
"This is interesting. Very interesting," Mr. Borgen says. He looks at my father. "Oh, do please sit down. We have much to discuss." Mum, Dad, and I all take a seat.  
Mr. Borgen looks at us all. "In normal cases, this would have been fatal."  
Dad and Mum both gasp. "In normal cases? How is this not normal?" Dad asks in a shaky voice.  
"You all know what thaws ice."  
"Heat?" I whisper.  
Mr. Borgen chuckles. "What thaws magical ice."  
Mum and Dad say it in unison. "True love."  
"Exactly. There have been many other cases when people with magic like yours have accidentally struck others with them, and the result has always been fatal. However, something very interesting has happened here." Mr. Borgen pauses. "You see, Anna's love for her sister, the one who struck her, was so strong and so powerful that it diminished the effects of the ice by a lot, who knows how much."  
"So... She'll live?" All the stress seems to have left Dad.  
"Yes. She will most definitely live."  
I sigh in relief.

"However, you will need to keep her warm as she recovers. And do keep in mind that the spell may have permenant effects on her appearance. Part of her hair is bound to stay white."

Dad nods.

"But there is one question I have," Mr. Borgen says. He hesitates for a fraction of a second before continuing. "How did this happen?"

Mum and Dad both look at me.  
I take a deep breath. "Anna and I were playing in the basement. I was creating snow for us to play in. She was jumping and I was catching her by making snow hills to land on. She was moving too fast and I just..."  
Mr. Borgen nods. "I see." He turns to Mum and Dad. "It pains me to say this, but it is necessary. While Elsa is still learning to control her magic, you should isolate her. Put her in a different room from Anna. Try to limit contact between the two. Once she comes to Hogwarts, she should be safe, but for now, please do as I say. It will make everyone safer."  
"We will do that," Dad says.  
"Oh and one more thing." Mr. Borgen looks straight at Dad. "Please erase Anna's memories of Elsa's powers, of her being a witch, of you two doing spells, of anything magic at all. It's- it's for her own good."  
Dad pauses. "We- we will do that as well. Thank you, Kai."  
"You are very welcome. You may go now."  
Isolate me? Will Anna and I ever get to see each other again? And erase all memories of magic? We're a wizarding family! How will life ever become normal again?

_Anna POV_

I wake up in my bed at home. "Elsa?" I whisper. "Elsa?" No reply.  
I get out of bed and put on my slippers. "Elsa?"  
Then I see it all. Her bed is gone. Her clothes are gone. Everything that was hers is gone.  
What is going on?  
I open my door and step into the hallway. "Mummy? Daddy?"  
Mummy comes rushing down the hall. "Anna, dear, how did you sleep?"  
"Where is Elsa?"  
Mum looks taken aback. "What?"  
"Where is Elsa?" I repeat.  
"Oh. She's just moved into a different room, that's all." I peek over Mum's shoulder. The guest room at the end of the hall is being redecorated.  
"Is she going to stay there?" I ask.  
"Yes, she is," Mum replies. She hurriedly changes the subject. "Why don't we go and have some breakfast?"  
She begins to walk downstairs. I start to follow, but look back at the guest room one more time. Elsa is opening the door!  
"Elsa!" I call. She turns to look at me. Panic floods her face. And she closes the door.  
"Elsa, wait!" I run down the hall and knock on the door. "It's me, Anna, remember?"  
A few seconds of silence.  
Finally, I hear a muffled voice. "I'm busy, Anna."  
Busy? Elsa is never busy. Suddenly I hear Mum from downstairs. "Anna? I made chocolate chip pancakes!"  
"Coming, Mum!"

_3 Months Later_

I haven't seen Elsa in forever. It seems that she hasn't come out of her room since the morning she moved. I've tried talking to her every morning.  
"Elsa?"  
"I'm busy, Anna."  
No such luck.

_3 Years Later_

"Elsa?" Every morning I've been coming to her door. Every time I get the same answer: "I'm busy, Anna." Who's busy all the time?  
"Elsa?" Still no answer. That's funny. I try the door. It's unlocked. I cautiously open it and  
peek inside. "Elsa?" No one's there. I open it all the way and step inside.  
The bed is neatly made. The clothes are all in the dresser, the books are all on the bookshelf. A laptop computer is on the desk. Nothing is out of place. Nothing but the piece of paper on the bedspread. I pick it up. A note is written in a neat cursive print that could only be Elsa's handwriting.

_Dear Family,_

_I'm sorry for doing this, but I had no choice. I couldn't take it, being cooped up like this. I couldn't take being away from Anna, I couldn't take her not knowing the truth. I'm sorry for deserting you, but I think it will be even better for your safety than what that Mr. Borgen guy had suggested. Once again, I am very sorry._

_Elsa_

Does that mean she's run away?  
"Mum! Dad! You need to see this!" They both come rushing up the stairs.  
"What is it, Anna?"  
"Elsa left a note!"  
They both run into the room. Dad picks up the note and both he and Mum read it. Their faces pale.  
"What truth was she talking about, Dad?" Mum shoots a panicked look at him.  
"Nothing, sweetheart. She meant nothing."  
"But this means she ran away, then, doesn't it?"  
"I'm afraid it does."  
"Why don't we go try to find her?"  
"There's no use." Never have I seen my parents look so defeated.  
"I-"  
"We won't ever find her, Anna," Dad says sternly. "Now go eat some breakfast."

* * *

Lately, the news has been full of stories of strange sightings. Ice sculptures found in the words, frosted trees and bushes even though it's the middle of summer. But today's story was the weirdest. Someone has been found frozen to death in their house. Frozen. Can you believe that? It's weird. And it's all about ice.

* * *

**A/N: Second chapter coming in a little bit!**


	2. The Visit

**A/N: Second chapter done. Please read and review! Remember, I don't own anything.**

_Anna POV_

The doorbell rings. Really, someone has to visit when I'm home alone.

I sigh and get up from my armchair in the living room. Trudging over to the door, I peek through the peephole. Some old guy is standing on the stoop. I cautiously open the door. "Hello?"

The man stares down at me (he is actually quite tall). A look of recognition passes over his face, and he smiles, a twinkle in his eye. "You must be Anna Arendelle?"

"How do you know my name?" Oops, probably shouldn't have said that. Now he knows who I am for sure. My mum said not to tell any of your personal information to strangers.

The man's smile grows wider. "I promise that I am not here to hurt you."

I hesitate, just for a fraction of a second. The man takes advantage of this pause and steps inside. I whirl around. "Wait a sec, why-"

"Ah, your parents are not home at the moment," he says, and looks back at me from his position in the middle of the living room.

"I- no, they're not." I sigh in defeat. If this man wanted to hurt me or steal something, he probably would have done it already. I close the door and walk inside myself.

"Would you like any tea or biscuits?" Might as well be polite.

"Oh, no thank you. I have been offered plenty already from other households," he says. Interesting. He's been elsewhere as well.

Surveying the room, he takes a seat and observes the paintings on the wall. Strange.

Suddenly he turns around and stares at me once more. "I realize that I have not formally introduced myself to you." He holds out a hand and continues. "I am Mr. Kai Borgen, the headmaster of Hogwarts School of Witchcraft and Wizardry."

Witchcraft and wizardry? What the...

He looks at me, as if waiting for a reaction. "Oh right," he mumbles to himself. "I forgot hat you didn't know." Then to me, he says, "You're a witch, Anna."

Witch? What kind of a joke is this?

"A witch? But aren't witches evil?" I ask.

"Oh, no. Quite the contrary, in fact."

"Sir, I believe you are mistaken. I'm- I'm just Anna."

"Well, 'Just Anna' did you ever make anything happen? Anything you couldn't explain, when you were angry or scared?"

I think. "Umm..."

_Flashback_

"Oh, but what can wimpy little girl do to stop me?" He said, smirking. I growled.

"I forgot. Nothing!" He laughed maniacally. All his cronies echoed him.

I balled my fists.

"Ooh, is wimpy girl going to take me on?" he taunted.

That was the last straw. "Shut your mouth!" I yelled.

"Make me!" He retorted.

I took a step towards him. "I said, shut your mouth."

He mimicked my move, towering above me, fists raised. "Try and make me, wimpy girl."

Then it happened. All so suddenly. I felt a gust of wind on my face. And then he was on the ground. Not hurt or injured, just on the ground. And he was mad.

"You- I know who you are!" he said, grinning that fiendish grin of his. "You- you and that lost sister of yours."

Why did he have to bring Elsa into this?

He grinned up at me, his face full of anger.

"You're a freak!" he spat out. "A freak!"

The words echoed through my brain. A freak. A freak. Freak. Freeeeeak.

His cronies helped him up and he stepped towards me.

"You," he hissed. "You'd better not come near me again, understand?"

I didn't move.

"Understand?" he said threateningly.

I nodded.

"Good," he said, satisfied. "Let's go."

And he stalked off, cronies following him.

_End Flashback_

"Umm... I suppose so."

Mr. Borgen smiles. "Then there's the proof!"

"But... I don't know how to control it!"

"That's where Hogwarts comes in, my dear. Our job is to educate young witches and wizards about magic."

"So does that mean... I have to go to Hogwarts?"

He chuckles. "Hang on, I haven't gotten there yet. You see, Hogwarts accepts all witches and wizards from around the country. You are a witch by blood, so you are automatically accepted."

"Really? I get to go to-"

On cue, the lock on the door clicks. I hear a faint, "Anna! We're home!"

Mr. Borgen smiles at me. "I'm afraid it's time for me to go." He reaches into his pocket and pulls out a sealed envelope. "Show this to your parents. It has all the details."

"But... Won't they be surprised when they find out I'm a witch?"

He stands up and dusts off his robes (a rather weird fashion). "Trust me, they already know," he says, winking.

And with that, he disappears with a loud crack.

"Anna? What was that noise?" My parents walk into the living room where I am still standing, clutching the envelope.

"Hello Mum, Dad." I take a deep breath. "There is something I need to show you."

I present the letter. Their faces pale.

"Anna?" Mum says.

"Yes, Mum?"

"I think we need to have a little discussion."

A/N: so there you go! Hope you like so far, please read and review. I'll update as soon as possible.


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